1. Field of the Invention
The present invention relates to a connection of the tubular ends of conduits or flow profiles which are associated with a cross-countercurrent matrix of a heat exchanger, and which are internally streamed through by a relatively cool gas (compressed air), to a suitably preperforated heat exchanger bottom of one or more manifolds formed for, respectively, the infeed or discharge of compressed air into or from the applicable heat exchanger matrix. In particular, the invention pertains to a method for the manufacture of such a connection.
2. Discussion of the Prior Art
A heat exchanger which is adapted for the utilization of the above-mentioned connection and a method for manufacturing such a connection has become known from German Laid-open Patent Application No. 29 07 810. In this known heat exchanger, there is provided a first compressed-air duct which can convey high-pressure air delivered, for example, from a compressor to a gas turbine engine having such an applicable heat exchanger matrix, in which the high-pressure air is then heated upon the matrix being subjected to the hot gas and will finally stream from the heat exchanger matrix into a second flow conduit which is connected to a suitable consumer, in this instance, to the combustion chamber of the gas turbine engine. For example, in this known heat exchanger the two separate flow conduits can be integrated into a common manifold from which the applicable heat exchanger matrix extends on both sides thereof as a subsequently U-shaped projection.
In connection with a known heat exchanger of that type, consideration must be given to the fact that about 12,000 or more tube connections with the bottom of the associated heat exchanger must be effected in practically a single brazing pass. During the manufacture of such heat exchangers, a brazing operation of such description presents a currently insurmountable risk factor in that relatively large brazing gaps must be provided between the respective tube ends and the associated walls of the holes, inasmuch as a sufficiently large gap is required in order to ensure a troublefree flowing of the brazing alloy, which is herein provided in a liquid molten state. Thus, there is always present the risk that during the process the liquid molten brazing alloy will deposit itself at different locations and that when it has cooled down there is no assurance present that it has filled the brazing gaps along their entire circumference.
Moreover, it has also been shown in practice that relatively large brazing gaps provided for the acceptance of large volumes of brazing alloy may ultimately impair the integrity of such connections. In addition thereto, comparatively thick deposits of brazing alloy in the respective gaps will adversely affect the corrosion resistance.